US2500990A

US2500990A - Apparatus for increasing production of oil wells

Info

Publication number: US2500990A
Application number: US607539A
Authority: US
Inventors: Beverly M Higginbotham; Ray S Hamilton
Original assignee: Linde Air Products Co
Current assignee: Linde Air Products Co
Priority date: 1945-07-28
Filing date: 1945-07-28
Publication date: 1950-03-21
Anticipated expiration: 1967-03-21

Description

March 21, 1950 B. M.'-HIGGINBOTHAM EI'AL 0,

APPARATUS FOR INCREASING PRODUCTION OF OIL WELLS Filed July 28, 1945 I 21 3 1 1v 37V 2 '32 3 7] 19 19 46 Z// 47 1M 45 w w? A -"'5 42 1 44 14 5 iii '40 l 45 1115 41 f i 2 'l- 39' if I 6 IAINVENTORS BEVERLY M.H|GG|NBOTHAM RAY S. HAM! TON ATTORNEY Patented Mar. 21, 1950 APPARATUS FORINCREASING.PRODUCTION OF OIL WELLS BeverlyM.'Higginbotham, Kenmore, and.Ray S. 'Hamilton, Manhasset, N. Y., assignors'to The Linde'Air'Prc'ducts Company a corporation of Application -July..28, 1945, Serial No. 607,539

3-Clairns. .1

This invention relates to. apparatus for igniting combustible material infitheibottom of an'oil well, and moreparticularlyior igniting a pool ofhydrocarbon'liquid inthe shothole of an oil well to initiate a cleanout treatment for eliminating cloggingmaterials in the oil sand at the shot hole.

After operating for a period of years,.oi1 wells often ceaseto produce oil and. gas at the rate that .is theoreticallypossibleaccordingto the state of depletion. of the .oil reservoir. Such reduction .of oil'fiow into the well fromthe oil sands oi'the .reservoir is mainly due to an accumulation of clogging. material such assludge and wax formations'. in the. sands at the walls of the shot holeat .thebottom of the well. Many methods of eliminating the-clo ng material have been proposed bustible .in'the shotiholeand burning such combustible by supplyinglto it an oxidant such. as .air oroxygen at alcontrolledxrate to burnthe combustible material including. the clogging material.

The clogging materialis thereby substantially completely gasified and removed. The process also includes a controlled spalling or breaking off of sandstone from thewalls :of' the shot hole whichserves to renewthe oil and. gas producing surfaces and eliminateany non-combustible c1cgging-material. Such a cleanout method is described and. claimed in .a co pending' United States applicationserial No.'60'7,540, filed July. .28, 1945, .by'L. A. B1iss,jR. S. Hamilton and 1B. M.'.Higginbotham.

.When a .pool of liquid hydrocarbon is used as the supply ofcombustible, the ignition thereof. is difiicult due to the quenching effect of .the oil pool. Attempts to effect ignition by merely dropping-into the well acartridge fusee or a flare, eitherypreviously ignited or .one .Which ignites by. impact, would notbe successful as the ignition device wouldbe smothered by the liquid'before e'flective ignition is obtained.

According to the present invention an adequate and certain ignitionisobtained byproviding a perforated. cage or basket securedto the lower end of. a pipe linestringextending into the well, through which the oxidant is tobe fed to the oil pool. in the bottom of the well. ,The basket is preferably made-of a. combustible material, for

.- An ignition: device .Lfitted :with a percussion fuse 2 may then be dropped through the pipe string into the basket and when the device strikes the basket or a combustible material placed in the basket, the pyrotechnic materialof the ignition device Will be ignitedjby the percussion fuse. The ignition device will create high temperature heat for igniting the combustible material of1the basket and the oil pool .when theoxidant isv supplied through the pipe string. The burning solid materials falling from the basket onto the oil surface will effect a thorough ignition of the oil surface. Alternatively; an ignition .device having a percussion fused end positioned upwardly may be packed in the basket before the. pipe string is lowered into the well and a weight, such as a cylinderof iron, may be dropped down thepipe string tohit the percussion fuse and setofi the ignition device. .Instead of a weight, a'second ignition device may be dropped downthe pipe line upon the one located in the basket. The

basket is. also. preferably filled with a. solidv easily ignitible combustible material which may be packed around the ignition device for supporting it. The basket is suspended close to the combustible in the shot hole and, if a liquid combustible is used, the basketis positioned just above such liquid pool to insure. that the ignition device is. not .quenched by the liquid. The ignition device, which is packed in the basket, is also preferably water and oil. proofed.

The principal object of the present invention is therefore to provide a simple but efiective .apparatus for igniting combustible in the bottom of an oil well. Other objects of the invention are to provide apparatus for igniting the combustible in an oil well which insure against the quenching of an ignition device by liquid in the well when such .device is dropped into the well, or when such .device is suspended at the lower end of the oxidant supply tube extending down the well; to provide a basket or cage for the reception of an ignition device .and easily ignitible material, which basket is removable after ignition by combustion. thereof to allow clear-access of oxidant to the oil pool; and to: provide an ignition device which is unaffected by water .or hydrocarbon liquids in the bottom of-the well.

These and other objects and novel features of this invention will become more apparent from the iollowingdescription taken in connection with the accompanying drawings, in which:

Fig. 1 is a diagrammatic elevational view, partly in section, of the upper and lower ends of anoil Well to be --cleaned out, showing therein an exemplary form of apparatus for igniting a combustible such as anoil rpool according to the invention;

Fig. 2 is an elevational view on a slightly enlarged scale of the basket at the lower end of the pipe line extending into the well; and

Fig. 3 is a sectional view on an enlarged scale of a suitable ignition device.

Referring now to the drawing and more particularly to Fig. l, the earth and rock through which the well is bored is indicated at l0, and the oil bearing formation at the bottom of the well, which in many instances is a porous sandstone, is indicated at H. The enlarged cavity 12 in the oil sand is termed the shot hole, and for a cleanout treatment the shot hole 22 is provided with a body of combustible, such as a pool of oil l3 in the bottom thereof. The oil well liner or casing I4 extends upwardly from a point generally some distance above the shot hole to a short distance above the earth where it is provided with a casing head 5. The casing head 15 may have an outlet iii in the side thereof for exhaust gas and also an upper flange ii which cooperates with a coupling is for supporting a pipe string l9 that extends down the Well into the shot hole, the coupling is being usually a part of the pipe string.

Above the coupling it the pipe 19 has interposed therein a T connection 20, having its side outlet coupled to an oxidant supply pipe 2!, controlled by a valve 22. Above the T 2i? a means for inserting an ignition device is provided, preferably comprising a quick opening gate valve 23, above which is a second gate valve separated from the first by a section of pipe 25.

As described in the aforementioned United States co-pending application, the lower end of the pipe string 19 preferably includes a section of tubing that is highly resistant to heat and oxidation such as stainless steel pipe to which is secured an ignition basket 2?. The basket is shown more clearly in Fig. 2 and is preferably made of a combustible material. A convenient form of basket may be made from a section of steel tubing having a diameter about the same as that of pipe H3 or of larger diameter than the pipe l9 as illustrated in Fig. 2. The upper end may be reduced if necessary and secured to a coupling 28, which is internally threaded for attachment to the pipe IS. The lower end of the basket is closed and may be provided with one or more holes 29. A plurality of slots 39 are preferably cut through the: side wall of the basket to ventilate the same. The slots preferably are longitudinally arranged and may be of any size desired. Preferably the slots are sufficient to remove one-third to one-half of the area of the walls. It is preferable that the basket or cage be strong enough to carry the weight of the entire pipe string. The reason for this is that it permits a convenient method of positioning the basket in the shot hole which is preferably suspended close to but above the surface of the oil pool l3, the level of which may vary considerably according to the size of the shot hole. To accurately position the basket, the depth of the oil pool is measured, preferably by lowering a measuring device into the well, withdrawing it and noting the height of the oil level above the bottom. The pipe string is then lowered until the basket touches the bottom of the well. The pipe string is thereafter raised an amount which is determined according to the depth of oil measured until the basket is just above the oil level. The tubing string is then secured in this position.

' Before the basket and pipe string is lowered into the well an ignition device D is preferably 4 packed and supported in the basket in a position with its fused end upward. Any ignition device that sets off by impact can be used. An effective device is a fusee capable of burning at least three minutes. The type known as a target identification flare is found satisfactory; however, a two and one-half pound incendiary bomb is also effective.

An easily ignitible and non-sinking solid material may also be packed around the ignition device, for example, charcoal or a mixture of charcoal and excelsior is found eifective. This is indicated at 3|. These combustible materials catch fire from the action of the ignition device and fall out of the cage onto the oil surface where they float and are very effective in aiding the ignition.

A suitable arrangement of the ignition device is illustrated in Fig. 3. The fusee or flare cartridge of cylindrical shape is indicated at 32. This should preferably have a combustible waterproof casing 33 sealed by a bottom cap 34. The upper end of the casing 33 is secured, for example, by cement to a coupling 35. The coupling 35 has vent holes 36 drilled through its wall at a point just above the open end of the casing 33. The coupling 35 is counterbored from above to provide a shoulder on which is seated a fuse holder 31. The fuse holder comprises a metal disc having a hole 38 therethrough, in which is supported a percussion fuse or cap 39 having a rim which engages the upper surface of the fuse holder disc 31. The disc 31 is held in place b an externally threaded plug 40 that engages cooperating threads 4| in the coupling. The plug 40 has an axial hole 42 therethrough for receiving the firing pin 43, such hole 42 being counterbored from below to provide a shoulder 44, that serves to retain the enlarged lower end 45 of the firing pin, which lower end is also pointed to engage and explode the cap 39. The upper end of the firing pin 43 is provided with an enlarged head 46 that serves as an impact surface and also serves to retain a light compression spring 47, which holds the firing pin normally out of engagement with the cap 39.

The cap 39 and the fusee 32 may be themselves waterproofed, but it is preferable that the ignition device he further protected from the action of water and other liquids by a sealing means that does not interfere with its operation. A suitable sealing means comprises a flexible cap or bag 50, which may be made of rubber, or combustible water and oil proofed plastic material. The sealing bag 50 is slipped over the firing pin end of the device and is sealed to the casing 33 by tying with string or wire 5!.

The ignition device shown in Fig. 3, is sup ported as in Fig. 1, within the basket 21 by pack ing the mixture of excelsior and charcoal around it so that the firing pin head is disposed upward and immediately under the end of the pipe 19. The pipe string is secured in position in the well as previously described and a second ignition device may be placed within the pipe section 25 with its head or firing pin end downward, the valve 2 1 being open to allow entry of the ignition device. The head end of the ignition device to be dropped in may preferably be provided with a conical protector to facilitate passage through pipe joints and to protect the bag 50 if the latter is employed. The valve 24 is then closed, a supply of oxidant is permitted to flow from the connection 2| through the pipe I9 until the pipe i9 is completely filled with the oxidant. The

gate valve 23 is then pulled open and the ignition device falls from the pipe section 25 down the pipe line l9 below where it strikes the ignition device D within the basket 21. Both ignition devices are thus fired. The impact drives the firing pin 43 against the cap 39 which explodes into the end of the casing 33, igniting the self-supporting pyrotechnical material therein. The hot gases at first blow out through the vent holes 39, which destroys the bag 59. The fusee 32 soon burns vigorously and ignites the charcoal and excelsior 3!, which falls out of the slots 353 of the cage 2'! onto the surface of the oil pool id. The oxidant flow is now turned on or increased and combustion becomes more vigorous. The heat generated soon raises the iron of the cage 27 to its ignition temperature which then is burned by the oxygen. The lower end of the basket will fall ofi to the bottom of the well and the path for fiow of oxygen toward the oil pool surface will then be clear.

It is not essential to drop a second ignition device down the pipe string l9. It will sometimes be preferable to drop a weight such as a cylinder of iron which falls against the upper end of the ignition device D in the basket 27 and by its impact drives the firing pin 43 against the cap 39. The spring 42 is only strong enough to hold the firing pin normally away from the cap 39, but offers no resistance to the impact of the weight. Alternatively, the ignition device D in the basket 21 may be omitted entirely, and an ignition device may be dropped down the tubing l9 into the basket. Upon the impact the ignition device will become ignited and contained in the basket above the oil level to prevent its becoming quenched.

It is also possible to omit the excelsior and charcoal or other combustible packing from the basket so that the flare alone will act to ignite the combustible in the well. As described in the aforementioned co-pending application, the rate of input of the oxidant at the time of ignition and for a short time thereafter must be kept relatively low until the combustion has been Well started. The preferred rate of oxygen input varies according to the amount of combustible and size of shot hole as well as certain other conditions encountered and may at first be as low as 500 cubic feet per hour, this rate later being increased to 1,000 to 9,000 cubic feet per hour.

Any unburned portion of the basket 21 that falls to the bottom of the well under the oil pool i3 will usually be burned after the oil pool is consumed. Other steel objects such as broken tools or pieces of pipe in the shot hole are also burned and reduced to iron oxide which settles to the bottom of the well and is easily removed by the tools employed to remove the cavings. The parafiin and sludge will also be eliminated and the oil producing surfaces will be spalled away and renewed to restore the well to high operating eifieiency.

It will be clear that the ignition device disclosed in Fig. 3 is merely an exemplary construction and that the percussion fuse portion in particular may be of any known type that is initiated by impact or alternatively a time fuse could be employed. The specific shape and dimensions of the basket 2'! can also be varied considerably so long as it is transversely small enough to pass down the well but big enough to receive or hold the ignition device. The tubing [9 is usually two inch nominal pipe size and the basket can be formed of similar sized tubing. It is also not essential that the basket be strong enough to support the weight of the entire pipe string but it is preferable that it be at least strong enough to support part of the weight so as to indicate by a reduction of tension at the derrick when the basket touches the bottom of the well.

What is claimed is:

1. Apparatus for igniting combustible material in the bottom or an oil well, which apparatus comprises a pipe string extending down the well; a perforated basket secured to the bottom of the pipe string; combustible easily ignitible material disposed within said basket; means for suspending the pipe string so that the basket is positioned at a predetermined distance above the bottom of the well; and means at the upper end of the pipe string for dropping an ignition means down the pipe string into the basket.

2. Apparatus for igniting combustible material at the bottom of an oil weil, which apparatus comprises a pipe string extending down the well; a perforated basket secured to the bottom of the pipe string; a percussion fused ignition device disposed in said. basket below the pipe string; combustible easily ignitable material within said basket and packed around and under said ignition device; means for suspending the pipe string so that the basket is positioned at a predetermined distance above the bottom of the well; and means at the upper end of the pipe string for dropping an ignition means down the pipe string into the basket.

3. Apparatus for igniting combustible material in the bottom of an oil Well, which apparatus comprises a pipe string extending down the well; an elongated basket secured to andcommunicating with the lower end of the pipe string, said basket being perforated in at least its lower portion and being formed of a metal combustible by oxygen; combustible, easily ignitible, and gas-pervious material disposed Within said basket; means for suspending said pine string so that the basket is positioned above the bottom of the well in predetermined relationship with respect to the oilproducing walls of the well; means for supplying oxidant comprising mainly oxygen to said pipe string; and means at the upper end of the pipe string for dropping an ignition means down the pipe string into the basket.

BEVERLY M. HIGGIN'BOTI-IAM. RAY S. HAMILTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 4,770 Noble Feb. 27, 1872 100,793 Dickey Aug. 30, 1870 797,529 Ollphant et a1 Aug. 15, 1906 1,239,247 Allison Sept. 4, 1917 1,457,479 Wolcott June 5, 1923 1,473,348 Howard Nov. 6, 1923 1,701,133 Ulmer Feb. 5, 1929 2,067,408 Morris Jan. 12, 1937 2,188,737 Hixon Jan. 30, 1940 2,382,471 Frey Aug. 14, 1945 OTHER REFERENCES Uren-Petroleum Production Engineering, 2nd edition, 1939, Oil Field Exploitation, pages 365, 366, McGraW-Hill, New York, N. Y,